Isotropic etching

Isotropic etching (e.g. wet etching or chemical etching) is a method commonly used in semi-conductor technology to remove material from a substrate via a chemical process using an etchant substance. The etchant may be a corrosive liquid or a chemically active ionized gas, known as a plasma. Unlike dry etching, isotropic etching does not etch in a single direction, but rather etches horizontally as well as vertically into the surface of the substrate. The horizontal etching may result in undercutting of patterned areas and significant changes in device characteristics. Isotropic etching may occur unavoidably, or it may be desirable for process reasons.